I have the Z1 installed. I have a torx driver to unscrew it. I even have the 2.5 inch to 3.5 inch ata adapter to put the drive in my desktop (which seems to be always open with stuff dangling out of it). But I have this nagging fear I will mess something up :( if I start to mess with it. How cool would it be that you could just put in the adapter and read it in a standard PC. I should probably rip a couple albums to the drive to see the directory layout.
I heard that the Z1 is running Windows for mobiles 5. I haven't confirmed this yet, but it sounds good. If so, I wonder how they formatted the drive.
I would think that just to be safe, you might want to have the unit compleately removed from your car (no power at all) to be safe if you pull the drive out.